1. Technical Field
The present invention relates to a light guide plate used for a head mounted display or the like that is mounted on a person's head for use, and a virtual image display apparatus incorporating the same.
2. Related Art
Recently, as virtual image display apparatuses that enable formation and observation of virtual images such as a head mounted display, various types are proposed in which a light guide plate guides an image light from a display element to the pupils of the observer's eyes. As a light guide plate for such virtual image display apparatuses, a technique is known in which an image light is guided by utilizing total reflection and the image light is also reflected by plural partial reflection surfaces arranged parallel to each other at a predetermined angled to a main surface of the light guide plate and is thus extracted from the light guide plate so that the image light reaches the retinas of the observer's eyes (see JP-T-2003-536102 and JP-A-2004-157520). The plural partial reflection surfaces provided on the light guide plate can be provided, for example, in the form of a reflection layer formed at a part with a sawtoothed cross section (see FIG. 5 of JP-A-2004-157520).
In the light guide plate having the reflection layer at the part with a sawtoothed cross as described above, a luminous flux having a certain total reflection angle or greater in the light guide plate may not become incident on the reflection layer and may pass through the reflection layer. Therefore, a luminous flux that is not used for image formation is generated and efficiency of use of light is lowered.